Electromagnetic brake.



(1. N. MAHONEY.

ELECTROMAGNETIC? BRAKE. APPLICATION FILED JULY 29, 1909.

Patented M21117, 1911."

2 SHEETS-SHEET 1.

' INVINfdR UNITED STATES PATENT OFFICE.

JOSEPH N. MAHONEY, 0E WILKINSBURG, PENNSYLVANIA, ASSIGNOB TO THE TEST-INGHOUSE AIR BRAKE COMPANY, OF PITTSBURG, PENNSYLVANIA, A CORPORATION OFPENNSYLVANIA.

Specification 0: Letters Patent.

ELECTROMAGNETIC BRAKE;

Patented Mar. 7, 1911.

Application filed July 29, 1909. Serial No. 510,191.

magnetic Brakes, of which the following is a specification.

This invention relates to means for bra-king electric motor drivenvehicles, and more particularly to a system in which the mo tors areconnected up to act as generators, the generative action itselfconstituting a brake and in some cases the current generated is alsosupplied to a local brake circuit containing electric brake devices.

It has heretofore been proposed to employ motors with auxiliary poles orinterpole field coils for the purpose of generating in the armaturecoils compensating elect-ro-motive force as each armature coil isundergoing commutation, so that commutation is effectedwithout excessiveor destructive sparking (ma whcreheavy currents are being generated.

W here a plurality of electric motors are employed for braking it isusual to connect up the motors in multiple groups or units,

each unit consisting of two or more motors.

With such an arrangement, it has been found that as no two motors can bemade in practice to generate exactly equal electromotive forces, thestronger machine will overcome the elcctro-motive force of the weakermachine and reversing -the current flow therein, will operate the Weakermachine as a motor, thus interfering with the braking functions of theapparatus. It has been proposed to obviate this difiieulty as to theordinary types of motors by either providing what is termed anequalizing connection across the connections between the fields and thearmatures, or by cross connecting thefield of one motor with thearmature of the other, so that the generative action of each motor isequalized. In the case of, inter-pole motors, however, an equ-allzlngconnection across the armature leads will.

not be effective for the desired purpose, because the machines may stillact as generators in a circuit formed through the equalizing connection,the interpolevfield coils,

sparking liable to be produced under conditions at the commutator.

The principal object of my invention contemplates the cross connectionof the main field of one motor with the armature of another motor ineach group or unit and the provision of an equalizing connection adaptedto connect a main motor field of one unit or group with a main motorfield of another unit. By this means each unit is compelled such togenerate in the same direction while one unit is prevented fromovercoming another unit by reason of the equalizing connection.

In the accompanying drawings; Figure l is a diagrammatic view of aninterpole motor equipment, showing the motor controlle'rs developed andthe controlling circuits and embodying my improvement and Fig. 2 adiagrammatic view of the circuits as formed in the first brakingposition.

To illustrate an application of my improvement the drawings show a fourinterpole motor equipment the circuit connections of which are governedby a running controller C and a braking controller 13. Therunningcontroller C may be operated in the usual manner to govern the movementof the car and if it is desired to apply the brakes, the runningcontroller is thrown to off position and the braking controller B ismoved to its first braking position, the brake switch A being alsoshifted to the position marked brake. The circuits formed in thisposition will then be as shown in Fig, 2 of the drawings and may betraced as follows; starting at point A the circuit is through armature1., interpole field coil AA E points EC and WM and cross connect-ion 5to point F thence through field coil of motor No. 3, connection Eand-points E M and F G. Similarly starting at point A the circuit isthrough armature 3 interpole field coil AA connec tion E points EPO andPM, cross connec tion 6 to 'point F and thence through the main fieldcoil of motor No. 1 to points E Mand I C. Points A and A and points WCand F G being respectively connected,

a unit or group of two motors, having the of connecting wire G whichjoins points in the circuits of the two motor units, and wire B, whichconnects the armature leads A A A and A through the respective localresistances 13* to inclusive and B 'to B inclusive and th commonresistance B to B Connected in parallel in the local brake circuitbetween the circuit wires G and B are brake magnet devices 7 and 8. Itwill now be evident that the movement of the vehicle will operate themotors as generators to supply current to the local brake circuit andthus effect the braking of the car.

In carrjfing out my invention the field coil of one motor of one groupor unit is connected to a field coil of one motor of the other group andaccordingly from the connecting wire an equalizing wire 9 leads toconnecting wire 10, so that the field coil of motor No.1 is connectedwith field coil of motor No. 4. It will now be seen that the output ofeach individual'motor is equalized by means of the cross connectionwhereby the armature oi. one motor feeds the field of the other motor ofthe unit, so that bucking within the unit is prevented, while anytendency or one of the units to generate a higher elcctio-1notive forcethan the other unit is checked by means of the equalizing connection 9.v

It will be understood that although a specific construction is shown inthe drawings, in order to illustrate an application of my invention, Ido not mean to limit the invention, as it is evident that the samemay beemployed in other ways, for instance the brake devices 7 and 8 may notbe employed, in some cases, and the circuits may be so connected as toreturn the current to the line, the generative action onl of the motorsbeing employed to effect the raking action.

Having now described my invention,what I claim as new and desire tosecure by Letters Patent, is

1. In an electric braking apparatus, the combination with a plurality ofmotors connected up in groups to act'as generators, of

a connection, from a field of one of the motors of one group to thefield of a motor of another group.

2. In combination with a plurality of mo- 'nected u units an adapted toact as generators for tors adapted to be connected up in groups to actas generators for braking purposes, I

group}.

3. 11 an electric braking apparatus,-the

combination with a plurality of motors conto form a series of two ormore braking purposes, each unit havingthearmature of one motor crossconnected to the field of another motor, of an equalizing connectionadapted to connect a Hold of one ofthe motors in one unit with a fieldof one of the motors in another unit. V

4. In an electric braking apparatus, the combination with a plurality ofelectric m0- tors of the type having main and auxiliary fields, of meansfor connecting up the motors in groups to act as generators for braking,a main field of one motor in a group being cross connected to anarmature of another motor of said group and an equalizing connectionadapted to connect a main motor field'of one motor of a group with amain motor field of a motor of another.

group.

5. In an electric braking apparatus, the combination with-interpolemotors adapted to be connected up in generative units of two motorshaving the main field of one motor cross connected to the armature ofthe other motor for su plying current to a local brake circuit, 0 anequalizing connection from the main field of a motor in one unit to themain field of a motor in another unit.

6. The method of operating a plurality of motors as generators to supplycurrent for braking purposes which consists in connecting up the motorsin groups with the field of one motor in each groupconnected to thearmature of another motor in the group and in connecting the field of amotor in one group with the field of a motor in another group.

In testimony whereof I have hereunto set m hand.

y JOSEPH N. MAHONEY.

Witnesses:

WM. M. Canr, A. M. CnnMnN'rs.

